The invention relates to a motor vehicle having a jump-start device, wherein the motor vehicle has an internal combustion engine with a starter motor, the motor vehicle is equipped with at least two on-board electrical power subsystems which are coupled together via an electric coupling element, each on-board electrical power subsystem has at least one rechargeable electrical energy storage device, and the motor vehicle has a jump-start support terminal.
In general, the on-board electrical power supply of motor vehicles is equipped with a start battery, to start the engine by means of a starter motor, and to supply consumers with electrical power when the alternator does not sufficiently meet the needs for electrical power. As such, the duties of the starter battery go beyond simply starting the engine, such that the starter battery in the modern development of vehicles is called the on-board electrical power supply battery, or SLI battery, for Starting, Lighting, and Ignition. If a battery failure or battery defect occurs, the vehicle can be jump-started and/or the battery can be recharged. In the case of jump-starting and also recharging, an external current and voltage source, such as a charging device or the on-board battery of another vehicle (the donor vehicle), for example, is galvanically connected to the battery of the receiving vehicle. The electrical connection is established with conducting cables. A conducting cable set consists of two insulated conductors which terminate in clamps or pincers which are designed for the size of standard battery poles (see Standard EN 50342-2 “Lead-acid starter batteries: Dimensions of batteries and marking of terminals” and the DIN 72553 Standard “Battery jumper cable for road vehicles with combustion engines; dimensions, requirements, testing”). The positive conductor of the cable set connects the positive potentials, meaning by way of example the two plus poles of the receiving and donor batteries, or the plus pole of the receiving battery to the plus output of a charging device. The minus conductor establishes a shared connection to ground.
During a jump-start, high currents flow (near to the range of kiloamps), such that the conductors of the cable set have a corresponding large cross-section. In many vehicle models, the battery poles are not easily accessible—when installed in the trunk, for example. In this case, the plus pole of the battery is not contacted; rather a terminal which is galvanically connected to the plus conductor of the battery is contacted. This terminal is called a jump-starting support terminal, and is a connection which is designated in the vehicle and/or the vehicle owner's manual for the intended use of recharging and jump-starting, and is easily accessible from outside. It is typically located in the region of the engine compartment, and is easily accessible after the engine hood has been opened to connect a pole clamp. By way of example, a jump-starting circuit for a vehicle having a starter battery, said circuit being protected against the reversal of polarity, is described in U.S. Pat. No. 6,211,577 B1.
In addition, modern motor vehicles have an engine starting and stopping function, for engine drives which are purely based on internal combustion as well as electrically combined, hybrid drives with an applied voltage of 12 volts, meaning that the engine is stopped in suitable driving situations during operation of the vehicle, and is started again after a short period of time. Examples of this can be waiting at a red light or at a railroad crossing. Halting the operation of the engine leads to fuel savings. Due to the more frequent number of engine starts compared to vehicles with a stop-start function, and to the necessity of supplying electrical consumers with power via the battery during the time that the engine is stopped during operation of the vehicle, the vehicle battery is subjected to great demands.
For this reason, vehicles with a start-stop function, or also vehicles with a high base electrical load, such as public or governmental vehicles, are frequently equipped with a second on-board electrical power supply which has its own battery, the same commonly being called auxiliary battery. The on-board electrical power subsystem, with the auxiliary battery, is separated from the on-board electrical power subsystem having the primary battery, the same also being called the base battery, by a battery cutoff relay and/or a DC converter. A cost-optimized variant is the use of a unidirectional DC converter without a battery cutoff relay. The DC converter is supplied with electricity by the on-board electrical power subsystem which has the primary battery, and transmits electrical power from its base on-board power supply input to its auxiliary on-board power supply output. Generally, the engine control unit is included in the input-side on-board power supply having the primary battery, and the starter motor is included in the output-side on-board power supply having the auxiliary battery. In U.S. Pat. No. 6,396,240 B1, a jump-starting device is described which has a third battery, for a vehicle having two on-board power supply batteries coupled via a DC converter.
A problem addressed by the invention is that of providing an improved jump-starting device in a motor vehicle having at least two on-board electrical power subsystems.
This problem is addressed by a jump-starting device according to the invention, wherein the jump-starting device is characterized by a multi-stage jump-starting circuit which galvanically separates the on-board electrical power supply and the jump-starting support terminal from each other when a first switching stage is selected, and which galvanically connects the on-board electrical power supply and the jump-starting support terminal to each other when a second switching stage is selected.
One advantage of the invention is that during normal operation of the vehicle, the on-board electrical power subsystems can be operated while galvanically isolated from each other. A power and energy management system implemented in the software of the vehicle mediates between the two on-board electrical power subsystems as an electrical coupling, via the DC converter. In exceptional situations, such as the vehicle being left a long time, for example, the on-board electrical power subsystems can be galvanically connected to each other by selecting the second switching stage of the jump-start switch. If, by way of example, one energy storage device has a deficiency of charge, an internal charge compensation can take place by means of the other energy storage device or the other energy storage devices.
According to one embodiment of the invention, the electrical coupling element which couples the on-board electrical power subsystems to each other is designed as a DC converter and/or a relay or switch.
No restriction shall be made on the general applicability of the invention if only a DC converter is presented in the present description.
According to one embodiment of the invention, it is possible to make an electrical contact with the jump-starting support terminal upon selection of the second switching stage of the jump-start switch, in order to charge the rechargeable electrical energy storage device, by an external voltage source, via the jump-starting support terminal.
This embodiment has the advantage that the jump-starting device enables the recharging of all energy storage devices by an external voltage source. All energy storage devices are galvanically connected to the external voltage source, such that the charging power is limited by the charge absorption capacity of the energy storage device or by the current releasing capacity of the external voltage source.
According to a further variant of the invention, it is possible to make an electrical contact with the jump-starting support terminal upon selection of the second switching stage of the jump-start switch, in order to supply the starter motor with electrical power from an external voltage source for a jump-start of the internal combustion engine.
This has the special advantage that the motor vehicle can be jump-started by an external voltage source, such as a charging device or a starter battery of a donor vehicle, for example. In the second switching stage of the jump-start switch, all on-board electrical power subsystems and therefore all energy storage devices are galvanically connected to the external power source. A jump-start can also be carried out if all energy storage devices have been fully discharged—for example as the result of standing for a long time. The jump-starting device makes it possible for all control devices required for a start to be energized regardless of the specific topology of the on-board electrical power supply—i.e. regardless of which on-board electrical power subsystems the control devices are integrated in. In addition, the starter motor can be supplied with the very high starting current for an engine start of approx. one kiloamp, by the external current source.
According to a particularly preferred embodiment of the invention, the jump-starting support terminal is designed with a substantially cylindrical shape, meaning that it has a cylindrical base shape. The jump-start switch is designed with a substantially circular shape, meaning that it has a circular base shape. The jump-start switch encloses the jump-starting support terminal with a galvanic connection. The jump-starting support terminal and the jump-start switch have a shared pressure mechanism and/or a rotary mechanism by means of which the jump-start switch can be fixed in one of at least two prespecified setting positions with respect to the jump-starting support terminal.
The embodiment of the jump-starting device offers the advantage that the jump-starting support terminal is integrated into the jump-start switch, and there is a conductive connection between these two components.
According to one implementation of the present invention, wherein the first switching stage of the jump-start switch is selected, the jump-start switch is fixed relative to the jump-starting support terminal in an upper position, and when the second switching stage of the jump-start switch is selected, the jump-start switch is fixed in a lower setting position relative to the jump-starting support terminal. When the jump-start switch is fixed in the upper setting position, the peripheral surface of the cylindrical base shape of the jump-starting support terminal is geometrically shielded. When the jump-start switch is fixed in the lower setting position, the peripheral surface of the cylindrical base shape of the jump-starting support terminal is geometrically, and at least partially freely, accessible to make an electrical contact.
This configuration ensures that the jump-starting support terminal cannot be contacted with a clamp or pincer of a conventional starter cable or jumper cable when in the upper setting position. When in the lower setting position, the jump-starting support terminal integrated into the jump-start switch is exposed, such that its peripheral surface can be gripped by a clamp or pincer.
According to a further preferred embodiment, the jump-starting support terminal is connected to a non-conducting holder. An elastic spring element functions to provide return force, in the axial direction of the jump-starting support terminal, between the holder and the jump-start switch.
The elastic spring element exerts a force on the jump-start switch which is oriented away from the holder.
In addition, the jump-start switch can have at least one attached locking pin on the side of the circular base shape of the jump-start switch which faces toward the jump-starting support terminal, and the locking pin faces in the direction leading away from the radial center of the circular base shape of the jump-start switch and of the cylindrical base shape of the jump-starting support terminal.
The jump-starting support terminal preferably has a recessed first groove for each locking pin. The first groove guides the locking pin in the form of a tongue and groove connection in the axial direction of the jump-starting support terminal. The locking pin can be fixed in the upper setting position on the end of the recessed first groove which faces opposite the holder, by means of the return force of the elastic spring element. For each locking pin, the jump-starting support terminal has one recessed second groove which is oriented perpendicular to the first groove and which transitions into the first groove in an L shape on the end of the first groove which faces the holder. The second groove guides the locking pin in the form of a tongue and groove connection perpendicularly to the axial direction, and perpendicularly to the direction leading away from radial center of the cylindrical base shape of the jump-starting support terminal. This means that the second groove guides the jump-start switch around the jump-starting support terminal in a rotational manner. The locking pin can be fixed in the lower setting position in the second groove by means of the return force of the elastic spring element.
This embodiment of a tongue and groove connection between the locking pin or the locking pins and the grooves functions so that the jump-start switch can be brought into the upper setting position from the lower setting position in a reversible manner. The setting of the lower setting position proceeding from the upper setting position can be achieved in that a pressing movement of the jump-start switch in the direction of the holder is followed by a first rotary movement. Upon the pressing movement, the locking pin or locking pins guide the jump-start switch relative to the axial direction of the jump-starting support terminal until the recessed end, the same facing the holder, of the first groove is reached, and the locking pin or the locking pins can be guided into the second groove. If the pin or the pins are in the second groove, the jump-start switch is in the lower setting position relative to the jump-starting support terminal. The first rotary movement can be executed up to the point when the pin or the pins reach the recessed end, the same facing opposite the first groove, of the second groove. If the jump-starting support terminal has the combination of the first and the second groove implemented at least two times in the configuration, assurance can only be given that the rotary movement can technically be carried out if a second groove is located precisely between two first grooves. The setting of the upper setting position proceeding from the lower setting position can be achieved in that a second rotary movement which runs in the opposite direction of the first rotary movement is executed, until the pin or the pins reach the first end of the recessed second groove, said end facing the first groove, and are transitioned over into the first groove. The return force of the elastic element moves the jump-start switch relative to the jump-starting support terminal into the upper setting position.
According to a further variant of the invention, one conducting element is stamped onto the non-conducting holder for each on-board electrical power subsystem, wherein each on-board electrical power subsystem is galvanically connected by means of said conducting element. The conducting elements are galvanically isolated from each other. The jump-start switch is galvanically isolated from the conducting elements when the first switching stage of the jump-start switch is selected. When the second switching stage of the jump-start switch is selected, the jump-start switch is galvanically connected to the conducting elements.
This variant ensures that when the second switching stage of the jump-start switch is selected, the jump-starting support terminal has a conductive connection to the on-board electrical power subsystems. When the first switching stage of the jump-start switch is selected, the jump-starting support terminal is isolated from the on-board electrical power subsystems.
The invention is based on the considerations presented as follows.
In order to supply a motor vehicle with external current and voltage, the on-board electrical power supply of the vehicle has a jump-starting support terminal. Via the same, the on-board battery can be charged by means of an external voltage source or an external battery, for example in the production factory, during or after a long period of non-use, or when in a workshop.
The jump-starting support terminal is inadequate in vehicles with on-board electrical power supplies which have multiple energy storage devices. These are, for example, vehicles with start-stop functionality which have an additional auxiliary on-board electrical power supply with its own electrical energy storage devices as auxiliary batteries or auxiliary energy storage devices, said auxiliary on-board electrical power supply being separated from the base on-board electrical power supply via a switch or a unidirectional DC converter. The base on-board electrical power supply and the auxiliary on-board electrical power supply are electrically coupled to each other by the DC converter, but are galvanically isolated from each other. The electrical power transferred from the battery in the base on-board electrical power supply to the battery in the auxiliary on-board electrical power supply is determined by the specification of the DC converter. Typically, the DC converter is designed according to considerations of cost and constructed space for the normal operation of the vehicle. The sizing of the converter is determined on the basis of the average power to be recharged during the driving time, and is typically in the range of several hundred watts. The converter is typically designed as unidirectional and only enables a flow of energy from the on-board electrical power supply to the auxiliary battery. If, by way of example, both batteries have been fully discharged, such that both batteries must be recharged, the design of the DC converter prevents a recharging of the batteries within a reasonable period of time. Particularly the electrical power required for a start of the internal combustion engine, with brief (a period of several milliseconds) 600 to 800 amp [loads], cannot be transferred. This is also the case for auxiliary batteries which are no longer capable of a start, are defective, or have high resistance. The conventional connection of the jump-starting support terminal to the basic on-board electrical power supply enables charging the base battery externally, with a charging power which is typically on average a few hundred Watts, but does not allow an adequate charging of the auxiliary battery in a short time. As a result, it is not able to start the vehicle within a short time. From the opposite perspective, the connection of the jump-starting support terminal to the auxiliary on-board electrical power supply makes a bi-directional DC converter necessary for charging a discharged on-board battery. In addition, there is no option to galvanically connect the two on-board electrical power supplies via an electrical switch upon a complete failure of the voltage supply in one or both of the on-board electrical power subsystems, because the switch itself cannot be switched when the voltage supply in the vehicle fails. In addition, the jump-starting support terminal, in combination with an electrical switch, must by necessity be on the side of the power supply network which supplies the switch. If only the battery in the power supply network which supplies the switch fails, an external voltage source must be used, because no internal compensation charging occurs via the other battery when the switch is open.
One suitable measure for ensuring to the greatest degree possible the ability of the vehicle to be jump-started and to be charged externally is the integration of a mechanical switch element for the purpose of connecting the on-board electrical power supplies for an external charging or for a jump-start. The integration of the mechanical switch element is preferably realized together with a mechanical logic device added to the jump-starting support terminal, said logic device only enabling an external conductive connection to the jump-starting support terminal, and the further on-board electrical power supply, if the on-board electrical power subsystems are galvanically connected to each other.
The integration of such a mechanical switch element comes with various advantages. The configuration ensures an effective external emergency power supply to one of the on-board electrical power subsystems when another on-board electrical power subsystem fails. A vehicle operator can carry out a jump-start as before. All on-board electrical power subsystems are supplied with electrical power via an access point from outside. When the vehicle is in the service workshop or in the vehicle production plant, all of the batteries can be charged with a single charging device.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one preferred embodiment when considered in conjunction with the accompanying drawings.